Cisco Bug: CSCvs05554 - multicast boundary configuration blocks PIM hellos when using ip multicast boundary with ACL on SVI
Nov 20, 2019
- Cisco Catalyst 3850 Series Switches
Known Affected Releases
Symptom: PIM Hellos dropped on ingress on a C3850 switch stack when using ip multicast boundary with ACL on SVI tested s/w version and it seems that multicast configuration was working in 3.6.6 code and broke in 3.6.7 , 3.6.8 and 3.6.9 . The configuration works in code 3.7.3, 3.7.4 and 3.7.5 . Also tested in latest 16.x image i.e. 16.12.1 Conditions: the PIM hellos from the neighboring router are arriving on physical ingress interface correctly. The packets appear to be dropped somewhere along the path to the control plane. the PIM Hellos should be arriving on VLAN 1001. The running configuration for SVI interface is as follows: Standard IP access list local-multicast-bound 10 permit 184.108.40.206, wildcard bits 0.0.255.255 interface Vlan 1001 ip address 30.253.0.X 255.255.255.252 no ip redirects no ip proxy-arp ip wccp 52 redirect in ip pim sparse-mode ip multicast boundary local-multicast-bound <<<<<<< The issue is caused by the multicast boundary configuration on the SVI. This configuration is meant to filter out certain multicast groups from having Mroutes built on a given interface. These are controlled via an ACL attached to the configuration For reference, PIM Hellos are sent to 220.127.116.11. With this multicast boundary command configured, the switch stops seeing the router as a PIM Neighbor. The neighbor router continues to see the switch (3850) as a PIM Neighbor.
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